1. Field of the Invention
The present invention relates generally to railroad Hotboxes and more specifically it relates to a smart thermal imaging and inspection device for wheels and components thereof for the automatic inspection and analysis of railroad car wheels or other wheeled vehicles.
2. Description of the Related Art
It can be appreciated that various forms of thermal imaging have been in use for years reading the temperature of wheels. A technology termed the Hotbox is the most common device and is found on railroads and uses infrared temperature measurements.
One type of system for measuring impermissible temperature increases of railway rolling stock wheels that are running hot includes an infrared temperature receiver which is usually located close to the rails so that an active window that subtends an angle to the normal can detect the bearings of a moving railroad car. A short period of time is available for temperature measurement, particularly at higher speeds.
The detection of the hottest point of an axle or a bearing can obscured or difficult to read in some instances. Wide scanning beams transverse to the longitudinal direction of the rail with an integrated signal have been used to some success. However, the integration that is provided by the detection of a relatively wide area in the longitudinal direction of the axles leads overall to a relatively small difference of the signals that are measured, so that reliable analysis is not possible without some difficulty. In the case of relatively complete bearing covers, impermissible heating can only be detected over a small part of the axial length of an axle since, by comparison, the other areas are significantly cooler. Some systems propose using rotating and oscillating mirrors to overcome such problems in the art.
One problem with the conventional Hotbox is that it employs a single pyrometer to determine temperature. Another problem with conventional Hotbox technology is the viewing window can easily become blocked due to leaves and other objects blocking the view due in part to the fact the Hotbox faces towards the sky. Another problem with conventional Hotbox technology is that weather conditions can block the field of view. The fundamental problem when using Hotbox or similar infrared technologies is that emissivity (the ability of a surface to emit radiation, measured as the ratio of the energy radiated by a surface to that radiated by a black body at the same temperature) correction is overlooked and actual temperature measurements can be in error by greater than twenty percent.
In addition, commercial vehicles, such as trucks, are involved in hundreds of thousands of crashes, resulting in thousands of fatalities each year. In many cases, defective brakes or tires are a factor in these crashes. Infrared brake screening technology has been employed to help identify maintenance needs before these deficiencies create problems on the road, such as a system which screens for brake defects and produces results in seconds. In one system, as a commercial vehicle decelerates to enter a roadside inspection facility, the system scans the vehicle's wheels with an infrared camera. The screen displays thermal images of the wheels, showing their relative temperatures. Because the application of brakes creates heat, the wheels with functional (warm) brakes appear bright white in the infrared image, while the wheels with inoperative (cold) brakes appear dark. The color image helps the operator easily identify a vehicle with functional or inoperative brakes.
Again, significant problems with conventional Hotbox technology include a single spot pyrometer used to determine temperature of a wheel that is three feet in diameter and that the viewing window easily become blocked by leaves, weather conditions can and other objects.
The present invention provides a smart thermal imaging and inspection for wheels and components thereof which substantially departs from the conventional concepts and designs of the prior art and improves upon the art by providing for the automatic inspection and analysis of railroad car wheels or for wheeled objects such as semi-trucks at weigh stations, sub-way cars or any wheeled device that has a bearing subject to such problems.